<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="test"></div>

  <script src="../js/react.development.js"></script>
  <script src="../js/react-dom.development.js"></script>
  <script src="../js/babel.min.js"></script>

  <script type="text/babel">
    class Life extends React.Component {

      state = {opacity: 1}

      death = () => {
        // 卸载组件
        ReactDOM.unmountComponentAtNode (document.getElementById ('test'))
      }

      // 组件挂载完毕
      componentDidMount () {
        this.timer = setInterval (() =>{
          let {opacity} = this.state
          opacity -= 0.1
          if (opacity <=0) opacity = 1
          // 设置新的state
          this.setState ({opacity})
        }, 200)
      }
      
      // 组件将要卸载
      componentWillUnmount () {
        clearInterval (this.timer)
      }

      // 初始化渲染 状态更新之后
      render () {
        return (
          <div>
            <h2 style = {{opacity: this.state.opacity}}>学不会怎么办</h2>
            <button onClick={this.death}>不活了</button>
          </div>
        )
      }
    }
    // 渲染到页面
    ReactDOM.render (<Life/>, document.getElementById ('test'))
  </script>
</body>
</html>